Topic: Drilling holes in a Mac baffle for better sound.??..

[bender01]

Im thinking of doing this to my 73 350f. Probably on the inside first so I can plug them with something if it doesnt work. Im hoping to get a meaner sound without losing power. It cant afford a loss in power. I currently have the baffle packed with stainless steel scrubbies to quiet the tinny sound. When I got the bike it had a 2>1 exhaust on each side without baffles. Ran poor but teenagers would cover theyre ears in pain at stoplights.Maybe drilling the first (wall )?so that pressure is forced into the last chamber? Someone here had a pencil sketch of how the mac baffle works. Im sure that someone has done this to a 550, 750 too. Let me know what not to do.Im willing to test an idea.
       Thanks

[KingCustomCycles.com]

I have had good luck with the 17" reverse cone muffler from emgo on a 2-1 Mac header:

http://www.crc2onlinecatalog.com/Index_Main_Frame.htm

Video of the sound here on a 750 cafe:

http://www.kingcustomcycles.com

You can buy replacement baffles to fit the Mac mufflers if you ruin one or want to experiment.  I have welded up baffles from scratch to get the sound I was looking for.  Drilling holes and packing with header wrap are my preferred methods of modification. I hope this helps some.

[bender01]

Well its done and it does sound a little more throaty. Very happy with it. Put on 35 miles and Ill ride it awhile checking the plugs and I might drill more holes in the tubes! Didnt seem to lose any power or gain any. Ditched the ss scrubbies too. Did find a replacement baffle too if it all goes wrong. Thanks

[paulages]

i took the baffle out of my mac, cut the baffle tubes off a couple inches from the end plates, wrapped perforated sheetmetal around it into a tube connecting the two ends, wrapped fiberglass around it, and reinstalled. turns your whimpy stock mac muffler into a nice sounding glasspack, which isn't really all that loud until you open it up.

[bender01]

Paulages, that sounds like a great idea. Will Auto Zone or Napa have the fiberglass I need? Is it a roll of fiberglass? Ill start searching now. Thanks.

[paulages]

Paulages, that sounds like a great idea. Will Auto Zone or Napa have the fiberglass I need? Is it a roll of fiberglass? Ill start searching now. Thanks.

honestly, you can use pipe insulation which is sold in small rolls, but you can buy the "proper" stuff at a car or bike shop.

[MJL]

I don't like the mac baffle either. I stuck a flowmaster on the end of my 4-1 pipe just to hear how it sounds, very nice! The only problem is that it looks like ass.  I have been thinking of finding a stock muffler from a cbr600 or something to fit on.

[coneeng]

Stainless steel wool works well to change the pitch of the sound.  It lowers the note but doesn't really lower the db level.  It just makes it seem like it to the ear.

[ColinMc]

I've used "Moose" packing material meant for two stroke dirt bikes and it works great...I think that was the brand lol.

[KB02]

I've used "Moose" packing material meant for two stroke dirt bikes and it works great...I think that was the brand lol.

"Moose" packing has a very unique smell to it. I repacked the pipe on my Ducati with the Moose packing. The biggest difference that I noticed was the smell.

[coneeng]

I've used "Moose" packing material meant for two stroke dirt bikes and it works great...I think that was the brand lol.

"Moose" packing has a very unique smell to it. I repacked the pipe on my Ducati with the Moose packing. The biggest difference that I noticed was the smell.

Smeel has been a big problem with a lot of the older style fiberglass packing material.  We think it is the flame retardent.  One batch smelled like the muffler had been put together with an old fish inside it so we quit using it.  We now have a new material called Silent Sport that seems to be working out extremely well.  A lot of aftermarket manufacturers use as well as some OEM motorcycle companies.

[KB02]

Smeel has been a big problem with a lot of the older style fiberglass packing material.  We think it is the flame retardent.  One batch smelled like the muffler had been put together with an old fish inside it so we quit using it.  We now have a new material called Silent Sport that seems to be working out extremely well.  A lot of aftermarket manufacturers use as well as some OEM motorcycle companies.

Where would one get some of this "Silent Sport" material you speak of?

[Sporkfly]

All I was able to find for the silent sport stuff was:

http://wardcycles.hypermart.net/merchant.mv?Screen=CTGY&Store_Code=WPI&Category_Code=SSrepack

Not sure about the store, never shopped there. It was a google find.

[mmtsquid]

Sorry to hijack - but if anyone has done the mod on the Mac exhaust, could you pull out the baffle and take a pic for me?